ASTM B734-97(2023)

Standard Specification for Electrodeposited Copper for Engineering Uses

ABSTRACT
This specification establishes the requirements for electrodeposited copper coatings used for engineering purposes including surface hardening, heat treatment stop-off, as an underplate for other engineering coatings, for electromagnetic interference shielding in electronic circuitry, and in certain joining operations. This specification does not cover electrodeposited copper used as a decorative finish, as an undercoat for other decorative finishes, or for electroforming. Coatings shall be classified according to thickness. Metal parts shall undergo pre- and post-coating treatment for reducing the risk of hydrogen embrittlement, and peening. Coatings shall be sampled, tested, and shall conform to specified requirements as to appearance, thickness, porosity, solderability, adhesion, embrittlement relief, and packaging.
SCOPE
1.1 This specification covers requirements for electrodeposited coatings of copper used for engineering purposes. Examples include surface hardening, heat treatment stop-off, as an underplate for other engineering coatings, for electromagnetic interferences (EMI) shielding in electronic circuitry, and in certain joining operations.  
1.2 This specification is not intended for electrodeposited copper when used as a decorative finish, or as an undercoat for other decorative finishes.  
1.3 This specification is not intended for electrodeposited copper when used for electroforming.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.03 - Engineering Coatings

Relations

• Replaces: ASTM B734-97(2018) - Standard Specification for Electrodeposited Copper for Engineering Uses
• Effective Date: 01-Nov-2023
• Refers: ASTM F519-23 - Standard Test Method for Mechanical Hydrogen Embrittlement Evaluation of Plating/Coating Processes and Service Environments
• Effective Date: 01-Dec-2023
• Refers: ASTM B849-02(2023) - Standard Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen Embrittlement
• Effective Date: 01-Nov-2023
• Refers: ASTM B832-93(2023) - Standard Guide for Electroforming with Nickel and Copper
• Effective Date: 01-Nov-2023
• Refers: ASTM B571-23 - Standard Practice for Qualitative Adhesion Testing of Metallic Coatings
• Effective Date: 01-Nov-2023
• Refers: ASTM B678-23 - Standard Test Method for Solderability of Metallic-Coated Products
• Effective Date: 01-Nov-2023
• Refers: ASTM D3951-18(2023) - Standard Practice for Commercial Packaging
• Effective Date: 01-Oct-2023
• Refers: ASTM B849-02(2019) - Standard Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen Embrittlement
• Effective Date: 01-Apr-2019
• Refers: ASTM F519-18 - Standard Test Method for Mechanical Hydrogen Embrittlement Evaluation of Plating/Coating Processes and Service Environments
• Effective Date: 01-Nov-2018
• Refers: ASTM B571-18 - Standard Practice for Qualitative Adhesion Testing of Metallic Coatings
• Effective Date: 01-Aug-2018
• Refers: ASTM B765-03(2018) - Standard Guide for Selection of Porosity and Gross Defect Tests for Electrodeposits and Related Metallic Coatings
• Effective Date: 01-Aug-2018
• Refers: ASTM B832-93(2018) - Standard Guide for Electroforming with Nickel and Copper
• Effective Date: 01-Jun-2018
• Refers: ASTM D3951-18 - Standard Practice for Commercial Packaging
• Effective Date: 01-May-2018
• Refers: ASTM B678-86(2017) - Standard Test Method for Solderability of Metallic-Coated Products
• Effective Date: 01-Nov-2017
• Referred By: ASTM B765-03(2023) - Standard Guide for Selection of Porosity and Gross Defect Tests for Electrodeposits and Related Metallic Coatings
• Effective Date: 01-Nov-2023

Overview

ASTM B734-97(2023): Standard Specification for Electrodeposited Copper for Engineering Uses sets out comprehensive requirements for the application of electrodeposited copper coatings used in industrial engineering. Developed by ASTM, this international standard governs copper coatings for technical and functional purposes, such as surface hardening, heat treatment stop-off, as a conductive layer under other coatings, electromagnetic interference (EMI) shielding in electronics, and certain joining operations. It explicitly excludes copper coatings used for decorative purposes or for electroforming.

By specifying classification, performance criteria, and test methods, ASTM B734-97(2023) enables consistent quality and performance in critical applications requiring electrodeposited copper. The specification also aligns with the World Trade Organization’s principles for international standardization, supporting globally recognized practices.

Key Topics

• Scope and Classification

  • Applies to electrodeposited copper coatings for engineering, not decorative or electroforming uses.
  • Classification is based on coating thickness (e.g., 25, 20, 12, or 5 μm).

• Coating Requirements

  • Coatings must display a smooth, defect-free finish on significant surfaces, free from blisters, pits, cracks, and other imperfections.
  • Stringent requirements for thickness, porosity, solderability, and adhesion.
  • Special pre- and post-coating treatments are required to address hydrogen embrittlement for high-strength steels.

• Sampling and Testing

  • Rigorous guidelines for sampling plans and the use of test specimens.
  • Comprehensive test methods cover coating thickness, porosity (e.g., ferroxyl test), adhesion, solderability, and embrittlement relief.
  • Testing procedures are referenced to other ASTM standards to verify coating quality.

• Pretreatment, Post-Treatment, and Packaging

  • Specifies pretreatments to reduce hydrogen embrittlement risk before copper deposition.
  • Post-coating heat treatments and peening are recommended as necessary.
  • Packaging should comply with commercial standards to protect the functional integrity of coatings.

Applications

Electrodeposited copper coatings per ASTM B734-97(2023) are critical in:

• Surface Hardening: Improving wear resistance of engineered metal parts.
• Heat Treatment Stop-off: Acting as a protective barrier to localize hardening or softening during thermal processing.
• Underplate for Engineering Coatings: Providing a conductive or sacrificial base layer below nickel, chromium, or other engineering platings.
• EMI Shielding in Electronics: Serving as a conductive EMI shield on electronic housings, PCBs, and other components to enhance signal integrity and reduce interference.
• Facilitating Joining Operations: Enabling brazing, soldering, or welding by serving as an intermediate metallic layer.

Industries benefiting from this standard include:

• Aerospace and automotive for improved component durability
• Electronics manufacturing for EMI shielding
• Industrial fabrication for reliable joining and enhanced surface performance

Related Standards

Key standards referenced or related to ASTM B734-97(2023):

• ASTM B320: Preparation of iron castings for electroplating
• ASTM B374: Terminology related to electroplating
• ASTM B487, B499, B504, B568, B588: Methods for coating thickness measurement
• ASTM B571: Adhesion testing of metallic coatings
• ASTM B678: Solderability testing
• ASTM B849, B850: Treatments to reduce hydrogen embrittlement risk
• ASTM B851: Shot peening for residual stress
• ASTM B765: Porosity and defect tests
• ASTM D3951: Commercial packaging guidelines

Employing ASTM B734-97(2023) ensures rigorous control of electrodeposited copper coatings, delivering functional performance, reliability, and compliance in demanding engineering applications worldwide.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B734 − 97 (Reapproved 2023)
Standard Specification for
Electrodeposited Copper for Engineering Uses
This standard is issued under the fixed designation B734; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope B568 Test Method for Measurement of Coating Thickness
by X-Ray Spectrometry
1.1 This specification covers requirements for electrodepos-
B571 Practice for Qualitative Adhesion Testing of Metallic
ited coatings of copper used for engineering purposes. Ex-
Coatings
amples include surface hardening, heat treatment stop-off, as
B588 Test Method for Measurement of Thickness of Trans-
an underplate for other engineering coatings, for electromag-
parent or Opaque Coatings by Double-Beam Interference
netic interferences (EMI) shielding in electronic circuitry, and
Microscope Technique (Withdrawn 2016)
in certain joining operations.
B602 Guide for Attribute Sampling of Metallic and Inor-
1.2 This specification is not intended for electrodeposited
ganic Coatings
copper when used as a decorative finish, or as an undercoat for
B678 Test Method for Solderability of Metallic-Coated
other decorative finishes.
Products
B697 Guide for Selection of Sampling Plans for Inspection
1.3 This specification is not intended for electrodeposited
copper when used for electroforming. of Electrodeposited Metallic and Inorganic Coatings
B762 Guide of Variables Sampling of Metallic and Inorganic
1.4 This international standard was developed in accor-
Coatings
dance with internationally recognized principles on standard-
B765 Guide for Selection of Porosity and Gross Defect Tests
ization established in the Decision on Principles for the
for Electrodeposits and Related Metallic Coatings
Development of International Standards, Guides and Recom-
B832 Guide for Electroforming with Nickel and Copper
mendations issued by the World Trade Organization Technical
B849 Specification for Pre-Treatments of Iron or Steel for
Barriers to Trade (TBT) Committee.
Reducing Risk of Hydrogen Embrittlement
2. Referenced Documents
B850 Guide for Post-Coating Treatments of Steel for Reduc-
ing the Risk of Hydrogen Embrittlement
2.1 ASTM Standards:
B851 Specification for Automated Controlled Shot Peening
B320 Practice for Preparation of Iron Castings for Electro-
of Metallic Articles Prior to Nickel, Autocatalytic Nickel,
plating
or Chromium Plating, or as Final Finish
B374 Terminology Relating to Electroplating
D3951 Practice for Commercial Packaging
B487 Test Method for Measurement of Metal and Oxide
F519 Test Method for Mechanical Hydrogen Embrittlement
Coating Thickness by Microscopical Examination of
Evaluation of Plating/Coating Processes and Service En-
Cross Section
vironments
B499 Test Method for Measurement of Coating Thicknesses
2.2 Military Standard:
by the Magnetic Method: Nonmagnetic Coatings on
MIL-R-81841 Rotary Flap Peening of Metal Parts
Magnetic Basis Metals
MIL-S-13165 Shot Peening of Metal Parts
B504 Test Method for Measurement of Thickness of Metal-
MIL-W-81840 Rotary Flap Peening Wheels
lic Coatings by the Coulometric Method
B507 Practice for Design of Articles to Be Electroplated on
3. Terminology
Racks
3.1 Definitions of Terms Specific to This Standard:
This specification is under the jurisdiction of ASTM Committee B08 on 3.1.1 significant surfaces, n—those surfaces normally vis-
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
ible (directly or by reflection) that are essential to the appear-
B08.03 on Engineering Coatings.
ance or serviceability of the article when assembled in a normal
Current edition approved Nov. 1, 2023. Published November 2023. Originally
approved in 1984. Last previous edition approved in 2018 as B734 – 97 (2018).
DOI: 10.1520/B0734-97R23.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or The last approved version of this historical standard is referenced on
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM www.astm.org.
Standards volume information, refer to the standard’s Document Summary page on Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
the ASTM website. Robbins Ave., Philadelphia, PA 19111-5094. Attn: NPODS.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B734 − 97 (2023)
position; or which can be the source of corrosion products that 5.4 If required by either party, the manufacturer of the parts
deface visible surfaces on the assembled article. When to be electroplated shall provide the electroplating facility with
necessary, the significant surface shall be indicated on the separate test specimens (see section 8.1).
drawing of the article, or by the provision of suitably marked
6. Coating Requirements
samples.
6.1 Appearance—The coating on the significant surfaces of
NOTE 1—When significant surfaces are involved on which the specified
the product shall be smooth and free of visual defects such as
thickness of coating cannot readily be controlled, such as threads, holes,
blisters, pits, roughness, cracks, flaking, burned deposits, and
deep recesses, and bases of angles, it will be necessary to apply thicker
uncoated areas. The boundaries of electroplating that cover
coatings on the more accessible surfaces, or to use special racking or both.
only a portion of the surface shall, after finishing as indicated
3.1.2 inspection lot, n—a collection of coated articles that;
in the drawing, be free of beads, nodules, jagged edges and
are of the same type; have been produced to the same
other detrimental irregularities. Imperfections and variations in
specifications; have been coated by a single supplier at one
appearance in the coating that arise from surface conditions of
time, or at approximately the same time, under essentially
the basis metal (scratches, pores, roll marks, inclusions, etc.)
identical conditions; and are submitted for acceptance or
and that persist in the finish despite the observance of good
rejection as a group.
metal finishing practices shall not be cause for rejection.
3.2 Definitions—For definitions of the technical terms used
NOTE 3—Electroplated finishes generally perform better when the
in this specification see Terminology B374.
substrate over which they are applied is smooth and free of deep scratches,
torn metal, pores, inclusions, and other defects. It is recommended that the
4. Classification
specifications covering the unfinished product provide limits for these
defects. A metal finisher can often remove defects through special
4.1 The electrodeposited copper is classified according to
treatments such as grinding, polishing, abrasive blasting, and special
thickness of the electrodeposit in the following table:
chemical treatments. However, these are not normal treatment steps.
When they are desired, they must be agreed upon between the buyer and
Class Minimum Thickness, μm
the producer.
25 25
20 20
6.2 Thickness—The thickness of the copper coating on the
12 12
significant surfaces shall conform to the requirements of the
5 5
x Thickness specified
specified class as defined in Section 4.
NOTE 2—For electroforming applications, that require much thicker
NOTE 4—Variation in the coating thickness from point-to-point on a
applications, see Guide B832.
coated article is an inherent characteristic of electroplating processes.
Therefore, the coating thickness will have to exceed the specified value at
some points on the significant surfaces to ensure that the thickness equals
5. Ordering Information
or exceeds the specified value at all points. As a result, the average coating
5.1 The buyer shall supply to the producer in the purchase
thickness on an article will usually be greater than the specified value; how
much greater is largely determined by the shape of the article (see Practice
order or engineering drawings; marked samples or other
B507) and the characteristics of the electroplating process. Additionally,
governing documents the following information:
the average coating thickness on an article will vary from article to article
5.1.1 Title, ASTM designation number (Specification
within a production lot. Therefore, if all of the articles in a production lot
B734), and date of issue.
are to meet the thickness requirement, the average coating thickness of the
5.1.2 Classification or thickness of electrodeposited copper production lot as a whole will be greater than the average necessary to
ensure that a single article meets the requirements.
(see 4.1),
NOTE 5—When electroplating threaded parts such as machine screws,
5.1.3 Significant surfaces if other than defined in 3.1.1,
care is required to avoid too much plate buildup on the crest of the thread.
5.1.4 Sampling plan (Section 7),
In such applications a maximum plate thickness allowable on the crests
may require that thicknesses in other areas be thinner.
5.1.5 Number of test specimens for destructive testing
(Section 8), and
6.3 Porosity—When specified, the coating shall be suffi-
5.1.6 Thickness, adhesion, solderability, porosity and num-
ciently free of pores to pass the porosity test specified in 8.4.
ber of pores acceptable, or hydrogen embrittlement tests and
6.4 Solderability—When specified, the coating shall meet
methods required (Section 8).
the requirements of Test Method B678.
5.2 Where required, dimensional tolerances allowed for the
6.5 Pretreatment of Iron and Steel for Reducing the Risk of
specified electroplated copper thickness shall be specified.
Hydrogen Embrittlement—Parts for critical applications that
are made of steels with ultimate tensile strengths of 1000 MPa,
5.3 In addition to the requirements of 5.1 and when the parts
hardness of 31 HRC or greater, that have been machined,
to be electroplated are supplied to the electroplater by the
ground, cold formed, or cold straightened subsequent to heat
buyer, the buyer shall also supply the following information as
treatment, shall require stress relief heat treatment when
required.
specified by the purchaser, the tensile strength to be supplied
5.3.1 Identity of the base material by alloy identification
by the purchaser. Specification B849 may be consulted for a
such as ASTM, AISI, or SAE numbers, or equivalent compo-
list of pretreatments that are used widely.
sition information,
5.3.2 Hardness of the parts, and
6.6 Post Coating Treatment of Iron and Steel for Reducing
5.3.3 Heat treatment for stress relief, whether it has been the Risk of Hydrogen Embrittlement—Parts for critical appli-
performed or is required. cations that are made of steels with ultimate tensile strengths of
B734 − 97 (2023)
1000 MPa, hardness of 31 HRC or greater, as well as surface 8. Test Methods
hardened parts, shall require post coating hydrogen embrittle-
8.1 The permission or the requirement to use special test
ment relief baking when specified by the purchaser, the tensile
specimens, the number to be used, the material from w
...